As far as stick out...
My 15x7s have 3.75" backspace.
Combined with my 10.50 wide tires and Rubicon flares (1" wider than Sport flares), my tread is almost fully covered. Full tread coverage may or may not be important in your locale.
The risk in running 7" wheels is that they are too small to run a 12.50 wide tire, should you decide later that you prefer a wider tire.
I chose 7's because I intend to always run a 10.50 wide tire.